1. Field of the Invention
The invention relates to suction cleaners, and in particular to a separator for a suction cleaner. In one of its aspects, the invention relates to a separator with a cyclonic airflow path to separate dirt and debris from air drawn into the cleaner. In another of its aspects, the invention relates to a separator that deposits the dirt and debris in a collection receptacle. In another of its aspects, the invention relates to a separator including structure for inhibiting the re-entrainment of debris that vacillates with upward airflows in the collection receptacle.
2. Description of the Related Art
Cyclone separators are well known. Some follow the textbook examples using frusto-conical shape separators and others use high-speed rotational motion of the air/dirt to separate the dirt by centrifugal force. Separation of the dirt/dust from the air is not difficult, but the problem of keeping the dirt separated from the airflow has not been adequately solved. There is a tendency for the separated debris to re-entrain into the airflow and thereby pass through the separator. Some minor amounts of fine dust usually do get through the cyclone and are filtered in secondary filters downstream to maximize dust removal. These filters are positioned anywhere from the cyclone exit port to the clean air exhaust port.
The U.S. Pat. No. 6,260,234 to Wright attempts to solve the re-entrainment problem by placing a main filter in the cyclonic chamber. In this case, the main filter becomes the main separator and re-entrainment becomes a non-issue. This technique is similar to the filters in utility vacuums; however this approach creates a new problem of blinding the filter. The main filter must be cleaned or replaced frequently due to poor cyclone separation and creates a customer satisfaction problem.
The U.S. Pat. No. 6,221,134 to Conrad et al. discloses another attempt to reduce re-entrainment in a cyclone separator. Conrad et al. disclose a particle-receiving chamber beneath the cyclonic fluid flow region by adding a particle-separating plate that extends across the width of the separator chamber and has a plurality of narrow slots. Even though there continues to be rotational motion in the receiving chamber, the particles find it difficult to re-entrain into the airflow. However, this technique also has a problem. Not all the dirt is small enough to pass through the slots and dirt accumulates in the slots and plugs the slots. This means that a significant amount of debris remains in the cyclonic fluid flow region and is subject to re-entrainment.
The U.S. Pat. No. 6,228,151 to Conrad et al. discloses yet another attempt to reduce re-entrainment in a cyclone separator. In this separator, a plurality of vertical radial vanes extends from the bottom of an outer wall of the separator to a central portion of the separator. A cap covers a significant portion of the inner radial length of the vanes.
The Holm-Hansen et al. U.S. Pat. No. 2,071,975 discloses a vacuum cleaner with a separate dust separator that includes a conical casing in which the dust is separated from air by centrifugal force and a dust receptacle separated from the conical casing by a plate that extends radially from the center of the separation chamber toward the wall of the conical casing. Particles that are separated from air in the conical casing pass through the annular space between the outer wall of the chamber and the outer edge of the plate and into the dust receptacle. A tubular member in the center of the conical casing is formed from four overlapping curved metal strips between which the separated air passes to exit the separator. A pair of parallel, horizontally disposed foraminous screens are mounted in the bottom of the dust receptacle to facilitate settling of the dust.
According to the invention, a vacuum cleaner comprises a housing defining a cyclonic airflow chamber for separating contaminants from a dirt-containing airstream and a cyclonic chamber inlet and an airstream outlet in fluid communication with said cyclonic airflow chamber. The vacuum cleaner includes a nozzle housing having a suction opening fluidly connected with the cyclonic chamber inlet, and an airstream suction source fluidly connected to the main suction opening and to the cyclonic airflow chamber for transporting dirt-containing air from the suction opening to the cyclonic airflow chamber. The suction source is adapted to establish and maintain a dirt-containing airstream from the suction opening to the cyclonic chamber inlet.
A dirt-collecting bin is mounted beneath the cyclonic airflow chamber and includes a bottom wall and a cylindrical sidewall. A separator plate between the cyclonic airflow chamber and the dirt-collecting bin separates the cyclonic airflow chamber from the dirt-collecting bin. The separator plate has a diameter less than a diameter of the cyclonic airflow chamber adjacent the separator plate to thereby define a gap between the separator plate and the cyclonic airflow chamber for passage of dirt separated from the dirt-containing airstream in the cyclonic airflow chamber. The passage of dirt through the gap is accompanied by an airflow having horizontal and vertical components between the gap and the bottom wall of the dirt-collecting bin, which airflow tends to entrain dirt particles therein. It is believed that this airflow may be elliptical in form.
Airflow inhibitors are present in the dirt-collecting bin to reduce the vertical component of the airflow, thereby tending to agglomerate and separate the dirt particles from the airflow.
In one embodiment, the flow inhibitors comprise at least one prong extending upwardly from the bottom wall of the dirt-collecting bin and positioned radially between a center of the dirt-collecting bin and the sidewall thereof. Preferably, the airflow inhibitors comprise a plurality of said prongs each positioned radially between a center of the dirt-collecting bin and the sidewall thereof. The prongs extend a portion of the distance between the bottom wall and the separator plate. Further, the prongs are rectangular in cross section with a long axis radially disposed in the dirt-collecting bin.
In another embodiment, the airflow inhibitors further comprise at least one fin that extends radially inwardly from the sidewall of the dirt-collecting bin. Preferably, there are two and only two fins. The fins are generally positioned vertically below the inlet. The fin or fins extend a portion of the distance between the bottom wall and the separator plate. The fin or fins extend between 40% and 60% of the distance between the bottom wall and the separator plate. Generally, the fins have a radial dimension between 2% and 10% of the radius of the dirt-collecting bin, preferably, between 3% and 6% of the radius of the dirt-collecting bin. In a specific embodiment, the fins have a radial dimension equal to about 4% of the radius of the dirt-collecting bin.